Now that we’ve discussed what eggs do in our baked goods, let’s see them in action! For this experiment, I baked two batches of brownies that were exactly the same, except one batch had less egg than the other.
Experiment Overview
Goal: To see and taste a difference in brownies containing fewer eggs
Recipe: Adapted from Sand Art Brownies
Method: Prepare two batches of brownie batter, one with the number of eggs written in the recipe (what we’ll call the “control”) and the other with one-third the eggs. Bake in the same pan with a foil divider, cool, and taste.
Results: In the brownies with less egg, we noticed
– Paler wet ingredient mixture and darker, thicker, greasier batter
– Easier removal from pan and darker color
– Lower rise and denser texture
– Harder, grittier texture
– Crumblier texture
– Worse flavor
Conclusions: Eggs are crucial for the rise, texture, and taste of brownies. They contain water, protein, and fat, which interact with other ingredients to produce the perfect brownie. Without enough eggs, brownies look more like shortbread cookies and don’t taste great.
Testing Method
Ingredients and Equipment
- 140g Baker’s Corner all-purpose flour
- 3/4 tsp Stonemill iodized salt
- 25g Baker’s Corner natural cocoa powder
- 52g Baker’s Corner light brown sugar
- 219g Baker’s Corner granulated sugar
- 2 Goldhen large eggs
- 152g Carlini canola oil, divided
- 8×8″ square pan, lined with foil to create two 4×8″ compartments and greased
Baking the Brownies
- Preheat oven to 350°F and prepare baking pan as described above.
- Whisk flour, salt, cocoa powder, and sugars together (440g total). Divide into two bowls (220g each).
- Whisk the eggs with 102g oil until evenly combined (200g total). Pour three-fourths of the mixture (150g) into another bowl. This is the wet ingredient mixture for the control brownies, and it contains 1.5 eggs. (Since this is a half-batch, it is equivalent to using 3 eggs for a full batch.) To the remaining mixture, add the remaining 50g oil. This is the wet ingredient mixture for the low-egg brownies, and it contains half an egg. (This is equivalent to using just one egg for a full batch.)
- Pour each set of wet ingredients into a bowl of dry ingredients and mix until just combined. Pour each batter into one side of the prepared baking pan, smooth the tops, and bake for 25 minutes. Remove to cooling rack, cool completely, then remove from foil, slice, and taste.
Results
To better understand these results, I suggest checking out the post about eggs in baked goods. We’ll also touch on leavening, starch, proteins, and fats.
Paler wet ingredient mixture and darker, thicker, greasier batter
The low-egg brownie batter looked different from the start. Its wet ingredient mixture was paler yellow in color, but once all the ingredients were combined, the low-egg batter was darker brown. It was also thicker and greasier than the control batter, as you can see in this photo.
Let’s talk about the differences in color first. The yellow color of the wet ingredient mixture came from the egg yolks. Because the low-egg wet ingredient mixture contained fewer yolks, it was lighter in color. When the wet and dry ingredients were combined, both batters turned brown from the cocoa powder. However, compared to the control batter, the low-egg batter didn’t have as many eggs to “dilute” the color of the cocoa powder, so the low-egg batter was darker brown.
Similarly, the missing eggs meant that the oil was more concentrated in the low-egg batter. As a result, the batter looked greasy. And because the low-egg batter was missing water from the eggs, it was drier and thicker than the control batter. In fact, it was so dry that we had to press it into the pan, whereas the control batter simply flowed into the corners.
Easier removal from pan and darker color
The differences in greasiness and color carried over after baking. Because of the high proportion of fat, the greasy low-egg brownies didn’t stick to the foil at all. On the other hand, the control brownies had to be peeled off. The low-egg brownies also retained their darker brown color after baking.
Lower rise and denser texture
Another difference between the baked brownies was in their height, shown below. Although both batches started off with similar amounts of batter, the low-egg brownies ended up flatter than the control brownies.
How can a couple eggs make that big of a difference? Remember, eggs contain a lot of water. As water heats up in the oven, it vaporizes into steam and expands, lifting the brownie batter around it. With fewer eggs and less water, the low-egg batter could not produce as much steam, so the brownies did not rise as high. This translated into a denser texture for the low-egg brownies.
Harder, grittier texture
Because they lacked water, the low-egg brownies were also harder than the control brownies. Water is important for the cooking process of starch, a component of flour that yields a soft texture reminiscent of cakes. (Think of pasta—you need plenty of water to cook the noodles.) Without sufficient water, the starch in the low-egg brownies wasn’t fully softened, and the brownies actually tasted more like cookies.
Another symptom of the missing water in the low-egg brownies was their gritty texture, which came from undissolved sugar crystals in the brownie. In muffin toppings and cookies, sugar crystals are deliberately used to add crunchiness. In brownies, however, the grittiness is unpleasant. The control brownies didn’t have this problem because the eggs supplied enough water to dissolve the sugar.
Crumblier texture
The low-egg brownies also crumbled more easily than the control brownies, indicating that they were not held together as strongly. In baked goods, structure comes from proteins. Proteins are responsible for the transformation of cooked eggs where they solidify and toughen in texture. In the control brownies, the same process sets the brownies’ shape and gives them just the right amount of chew. However, the low-egg brownies were missing a lot of egg proteins. Although there was enough protein to hold the brownies’ rectangular shape after baking, there wasn’t enough to make the brownies chewy rather than crumbly.
Worse flavor
In addition to their gritty, crumbly texture, the low-egg brownies tasted one-dimensional. In comparison, the control brownies had a more complex, rich flavor. The differences in taste can be partially attributed to fat content. Egg yolks contain fat, which improve flavor by adding richness and carrying flavor molecules. Since the low-egg brownies contained less fat, they did not taste as good.
Conclusions
Eggs have several functions in brownies. Their water content helps with rise and texture, their proteins contribute structure and chew, and their fats round out flavors and add richness. All of these roles are crucial to creating a brownie with a good texture and taste.
From the results of this experiment, if I had to substitute the eggs in this brownie recipe, I would make sure to replace their water, structural proteins, and fat. I’d probably start by adding milk (which contains both water and fat) and using bread flour for some or all of the all-purpose flour. Bread flour would increase protein content without weighing down or drying out the brownies with excess flour.
References
Corriher, S. O. Bakewise; Scribner: New York, 2008.
Figoni, P. How Baking Works, 3rd ed.; John Wiley & Sons, Inc.: Hoboken, 2011.
McGee, H. On Food and Cooking; Scriber: New York, 2004.
Nelson, D. L.; Cox, M. M. Lehninger Principles of Biochemistry, 6th ed.; Freeman, W. H. & Company: New York, 2012.